1. Field of the Invention
The invention relates to a crankshaft starter-generator for an internal combustion engine.
2. The Prior Art
A crankshaft starter-generator is disclosed in German Patent 199 41 705 A1. In this case, the stator of the starter-generator is torsionally coupled with a motor block of the internal combustion engine. The rotor of the starter-generator is coupled by torsional strength with the crankshaft of the internal combustion engine. Furthermore, a belt pulley is coaxially arranged with the crankshaft forming a carrier that is drive-coupled with the crankshaft and with the engine. The starter-generator is mounted eccentrically in relation to the crankshaft, and laterally on the motor. However, additional installation space is required for such an arrangement.
German Patent 19631 384 C1 discloses an electrical machine with a stator and a rotor arranged in the drive train of a driving aggregate. The rotor may be mounted, for example on a crankshaft of an internal combustion engine. An insulation against vibration is installed in the drive train. This insulation is integrated in the rotor of the electrical machine. The electrical machine may have the function, for example of a starter-generator.
Another starter-generator is disclosed in U.S. Pat. No. 1,770,468. The rotor of this starter-generator is connected with torsional strength to the crankshaft and to a coaxially arranged belt pulley. The stator of the starter-generator is connected to the body of the vehicle.
A crankshaft starter-generator is also disclosed in the prospectus xe2x80x9cDer Sachs Dynastartxe2x80x94Die neue Energie fxc3xcrs Autoxe2x80x9d [The Sachs DynaStartxe2x80x94The New Energy for the Car]. This crankshaft starter-generator is drive-coupled with a crankshaft of the internal combustion engine and serves both as a starter and generator. A stator of the starter-generator is mounted via a carrier on a motor block of the internal combustion engine and is coupled with torsional strength to the motor block. A rotor of the starter-generator is secured on a flywheel of the internal combustion engine, whereby the flywheel is torsionally coupled to the crankshaft of the internal combustion machine. The rotor is coupled with torsional strength to the crankshaft as well. The flywheel of the internal combustion engine is usually located between the motor block and the inlet side of a clutch. The output side is coupled with the transmission. However, the components located in this area are subjected to high temperatures. Therefore, the starter-generator requires intensive cooling in order to avoid damage to its windings. A further drawback of the known starter-generator is its integration into the drive train of the internal combustion engine which requires a change in the construction of the drive train. Furthermore, integrating the starter-generator into the drive train changes the installation measurements of the internal combustion engine, so that structural changes have to be made in the vehicle.
Furthermore, there is a need for installing starter-generators with different capacities depending on the type of vehicle or vehicle equipment involved. These starter-generators, however, differ from each other by their installation measurements, so that structural adaptations are also required.
An object of the present invention is to provide a compact design for a starter-generator that can be integrated into a conventional drive train of an internal combustion engine.
These objects are accomplished by providing a starter-generator drive-coupled to the crankshaft of an internal combustion engine. A stator is disposed on the inside of the starter-generator, and is torsionally coupled to the motor block. A rotor is disposed on the outside of the starter-generator and is drive-coupled with the crankshaft. A carrier is coaxially disposed with respect to the crankshaft and the rotor. The carrier is drive-coupled to the crankshaft and torsionally coupled to the rotor. Therefore, a compact type of construction is achieved for the starter-generator. This type of construction permits direct transmission of the force or moment between the crankshaft and the rotor via the carrier.
In the present invention, the starter-generator is arranged on the side of the internal combustion engine that is facing away from the driven side of the crankshaft, and the rotor is connected with the crankshaft via the carrier. Internal combustion engines of the type commonly known, mount the starter-generator at the end of the motor block that is associated with a belt drive of the internal combustion engine. Therefore, the starter-generator is located in a site where a reduction in the development of heat occurs, compared to a position located between the transmission and the motor block. A flow of cooling air can be directed to the site in a relatively simple manner. However, another important advantage of the starter-generator defined by the invention is that no structural changes are needed to install the starter-generator. It is also possible to install starter-generators with different dimensions depending on the required capacity, which makes it possible to realize a large variety of different types without requiring costly structural changes to the individual internal combustion engines.
According to a preferred embodiment of the invention, the carrier supports a belt pulley of a belt drive of the internal combustion engine. The carrier may be in the form of a belt pulley, which enhances a compact type of construction.
Preferably, the carrier or belt pulley and the rotor form an integral unit, i.e. the carrier or the belt pulley are formed on the rotor, or the rotor is formed on the carrier, or on the belt pulley. This facilitates the compact type of construction for the starter-generator.
In another preferred embodiment of the invention, the rotor contains, on a side facing away from the crankshaft, a projecting collar on which the carrier or belt pulley is formed. Therefore, different diameters can be obtained for the rotor and the carrier, or belt pulley in a simple way.